Spirochaeta Spi`ro*ch[ae]"ta, Spirochaete Spi`ro*ch[ae]"te, n. [L. spira a coil + Gr. ??? hair.] (Biol.) A genus of Spirobacteria similar to Spirillum, but distinguished by its motility. One species, the Spiroch[ae]te Obermeyeri, is supposed to be the cause of relapsing fever.